If you use the file cache driver (which is default) it’s an all-or-nothing thing.
If you’ld like to flush the cache yourself, you can use cache::flush(). But, as I said, this will clear the entire cache. This is by design since it cannot know if the thing you just changed isn’t pulled into another page somehow.
If you would like to have more control, you could try to setup your “own” cache logic by indeed following the explanations in the “old forum topic” :-).